A lens driver with camera shake reducing function utilizes the auto-focusing function to perform the focusing, meanwhile it causes the lens to swing in a direction at right angle to (orthogonal to) the optical axis direction of the lens according to the camera shake generated in photographing, so as to suppress the blurring of the image that is imaged on the image sensor.
For example, a lens driver with camera shake reducing function is proposed in patent document 1, which utilizes a linear spring member extending along the optical axis direction to support a focusing unit for focusing of the lens in form of suspending rack such that the focusing unit may swing, so as to suppress a blurring of the image.
FIG. 6 is an illustration of a lens driver 30 with camera shake reducing function from the prior art. FIG. 6(a) is a perspective view of the lens driver 30 with camera shake reducing function, FIG. 6(b) is an exploded view and FIG. 6(c) is an enlarged view of the main part. The optical axis of the not illustrated lens is set to Z (Z-axis) direction and two directions orthogonal to Z-axis are set to X (X-axis) direction and Y (Y-axis) direction, and a direction of the photographed object is set to forward direction of the optical axis direction (+Z side, front side).
As illustrated in FIG. 6(a), the lens driver 30 with camera shake reducing function is generally rectangular, and its central portion is opened in Z-direction in form of a circle, so as to hold the not illustrated lens. As illustrated in FIG. 6(b), the lens driver 30 with camera shake reducing function is composed of a focusing unit 31 and a camera shake reducing unit 32.
The focusing unit 31 is composed of a lens holder 33, a focusing coil 34, a magnet 35, a magnet holder 36, a plate-like spring member 37 and a separator 38. Furthermore, the camera shake reducing unit 32 is composed of a coil for swinging 39, a printed circuit board 41, a flexible printed circuit board 42, a linear spring member 40 and a base 43.
The lens holder 33 of the focusing unit 31 is a cylindric member which is opened in Z-direction and which serves to hold the lens on its inner circumference. The focusing coil 34 is wound, according to the shape of the outer circumference of the lens holder 33, onto the outer circumference of the lens holder 33. On the outer diameter side of the focusing coil 34, a magnet 35 formed by permanent magnet faces the focusing coil 34 with a gap in the redial direction. The magnet 35 is plate-like, and held by a magnet holder 36 in form of a box with four borders. Moreover, the magnets 35 are spaced at a interval of 90 degree around Z-axis in a manner that their magnet poles face X-direction and Y-axis.
The plate-like spring member 37 is composed of a front spring member 37A and a back spring member 37B. The inner circumference of the front spring member 37A and the back spring member 37B is connected with the end face on +Z side of the lens holder 33 and the end face on −Z side of the lens holder 33. The outer circumference of the front spring member 37A and the back spring member 37B is connected with the end face on +Z side of the magnet holder 36 and the end face on −Z side of the magnet holder 36. In this way, the front spring member 37A and the back spring member 37B support the lens holder 33 in form of suspending rack such that they may move along Z-axis.
Furthermore, on −Z side of the back spring member 37B, a separator 38 is arranged. The separator 38 clamps, together with the end face on −Z side of the magnet holder 36, the outer circumference of the back spring member.
When the focusing coil 34 is electrified, the focusing unit 31 built as described above generates a Lorentz force in Z-axis direction, which may move the lens holder 33 in Z-axis direction.
The camera shake unit 32 is built by stacking respective members on the plate-like base 43 which is opened in the center and oriented in Z-axis direction. In particular, a flexible printed circuit board 42 is mounted on +Z side surface of the base 43, and on the +Z side surface of the flexible circuit board 42, a printed circuit board 41 is mounted. On the printed circuit board 41, a coil for swinging 39 is arranged which is supplied with power externally via the flexible printed circuit board 42.
The coil for swinging 39 is wound along Z-axis, and is composed of X side coils for swinging 39X, which are arranged on −X side and +X side of the printed circuit board 41, and Y side coils for swinging 39Y, which are arranged on −Y side and +Y side. Furthermore, the coils for swinging 39 faces the −Z side surface of the magnet 35 at an interval in Z-axis direction.
The spring member 40 is a linear spring which extends in Z-direction and which is arranged on four corners of the base 43. An end of the spring member 40 passes through a connecting hole 43r formed on the base 43r and an connecting hole 37r formed on the front spring member 37A, so as to support the focusing unit 31 such that it may swing in X-axis direction and Y-axis direction. More specifically, as shown in FIG. 6(c), on the outer holding portion 37h of the front spring member 37A, a connecting hole 37r is formed, and on four corners of the base 43, connecting holes 43r are formed.
Furthermore, a shielding housing 45 is a box with a round opening, which surrounds the outer circumference of the focusing unit 31 and the camera shake unit 32.
When the X side coil for swinging 39X of the camera shake reducing unit 32 as built above is electrified, this X side coil for swinging 39X will generate a Lorentz force in X-axis direction, and the focusing unit 31 may be moved in X-axis direction using the reaction force generated on the magnet 35. Furthermore, as to the Y side coil for swinging 39Y, when this Y side coil for swinging 39Y is electrified, it will generate a Lorentz force in Y-axis direction, and the focusing unit 31 may be moved in Y-axis direction using the reaction force generated on the magnet 35.